Abstract:

Suaeda liaotungensis choline monooxygenase CMO, a key gene in betaine biosynthesis, was
introduced into tobacco genome byAgrobacterium tumefaciens mediated transformation. Molecular test showed
thatCMO had been integrated into tobacco genome and expressed properly. However, different transgenic lines
showed differentCMO copies, with lines of T1、T2、T6 being 1 copy, lines of T4、T5 being 2 copies and line T3
being 3 copies. And this might be a result of various insert sites ofCMO in the tobacco genome. All the
transgenic lines acquired enhanced oxidative stress induced by paraquat. When stressed with 10 μM and 20
μ M paraquat for 24 h, the transgenic lines had significant lower malondialdehyde content and higher
superoxide dismutase activity compared with wild type plants. In contrast, no significant difference of
malondialdehyde content and superoxide dismutase activity was found between the transgenic lines and wild
type plants under normal conditions. The accumulation of betaine in the transgenic lines might induced or
protected the activities of the antioxidant enzymes, which makes the transgenic plants suffered less from
oxidative stress as evidenced by lower electric conductivity. In conclusion, the overexpression of choline monooxygenase geneCMO in tobacco plants enhanced its oxidative stress tolerance ability, and geneCMO can be further used in some important crop plants such as corn and rice to improve their abiotic stress.